[Federal Register Volume 59, Number 176 (Tuesday, September 13, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-22627]
[[Page Unknown]]
[Federal Register: September 13, 1994]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 93-SW-27-AD]
Airworthiness Directives; The Enstrom Helicopter Corporation
Model F-28, F-28A, F-28C, F-28C-2, F-28F, 280, 280C, 280F, and 280FX
Series Helicopters
AGENCY: Federal Aviation Administration, DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: This document proposes the supersedure of an existing
airworthiness directive (AD), applicable to The Enstrom Helicopter
Corporation Model F-28, F-28A, F-28C, F-28C-2, F-28F, 280, 280C, 280F,
and 280FX series helicopters, that currently requires initial and
repetitive inspections of a certain main rotor transmission clutch
assembly (clutch assembly) for bearing roughness, noise, lock-up, or
improper oil level and, if necessary, replacement of the clutch
assembly. The current AD also requires replacement of the clutch
assembly at certain time-in-service intervals. This action would
require the same inspections and replacements as required by the
current AD, but would provide an additional approved replacement part
number and provide a reference to three additional manufacturer service
documents. The actions specified by the proposed AD are intended to
prevent failure of the clutch assembly, loss of control of the main
rotor system, and subsequent loss of control of the helicopter.
DATES: Comments must be received by October 28, 1994.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Office of the Assistant Chief Counsel, Attention:
Rules Docket No. 93-SW-27-AD, 2601 Meacham Blvd., Room 663, Fort Worth,
Texas 76137-4298. Comments may be inspected at this location between
9:00 a.m. and 3:00 p.m., Monday through Friday, except Federal
holidays.
The service information referenced in the proposed rule may be
obtained from The Enstrom Helicopter Corporation, Twin County Airport,
P.O. Box 490, Menominee, Michigan 49858. This information may be
examined at the FAA, Office of the Assistant Chief Counsel, 2601
Meacham Blvd., Room 663, Fort Worth, Texas.
FOR FURTHER INFORMATION CONTACT: Mr. Joe McGarvey, Aerospace Engineer,
Chicago Aircraft Certification Office, Airframe Branch, FAA, Small
Airplane Directorate, 2300 East Devon Avenue, Room 202, Des Plaines,
Illinois 60018, telephone (708) 294-7136, fax (708) 294-7834.
SUPPLEMENTARY INFORMATION:
Comments Invited
Interested persons are invited to participate in the making of the
proposed rule by submitting such written data, views, or arguments as
they may desire. Communications should identify the Rules Docket number
and be submitted in triplicate to the address specified above. All
communications received on or before the closing date for comments,
specified above, will be considered before taking action on the
proposed rule. The proposals contained in this notice may be changed in
light of the comments received.
Comments are specifically invited on the overall regulatory,
economic, environmental, and energy aspects of the proposed rule. All
comments submitted will be available, both before and after the closing
date for comments, in the Rules Docket for examination by interested
persons. A report summarizing each FAA-public contact concerned with
the substance of this proposal will be filed in the Rules Docket.
Commenters wishing the FAA to acknowledge receipt of their comments
submitted in response to this notice must submit a self-addressed,
stamped postcard on which the following statement is made: ``Comments
to Docket Number 93-SW-27-AD.'' The postcard will be date stamped and
returned to the commenter.
Availability of NPRMs
Any person may obtain a copy of this NPRM by submitting a request
to the FAA, Office of the Assistant Chief Counsel, Attention: Rules
Docket No. 93-SW-27-AD, 2601 Meacham Blvd., Room 663, Fort Worth, Texas
76137-4298.
Discussion
On January 23, 1989, the FAA issued AD 89-04-09, Amendment 39-6138
(54 FR 6391, February 10, 1989), to require initial and repetitive
inspections of certain main rotor transmission clutch assemblies for
bearing roughness, noise, lock-up, and improper oil levels. AD 89-04-09
also requires replacement of the main rotor transmission clutch
assembly (clutch assembly) when unairworthy, and establishes a 1,200
hours time-in-service retirement life on the clutch assembly. That
action was prompted by several failures of the clutch assembly. Based
on an analysis of the clutch assembly failure data, the FAA, in
conjunction with The Enstrom Helicopter Corporation and Formsprag, the
clutch assembly manufacturer, determined that the clutch assembly, P/N
28-13401-1 (Formsprag CL 40526-1 through -7), could not be safely
overhauled and returned to service. The FAA has determined that
premature failure of the clutch assembly due to a loss of lubricant
creates an unsafe condition. The requirements of that AD are intended
to prevent failure of the clutch assembly, loss of control of the main
rotor system, and subsequent loss of control of the helicopter.
Since the issuance of that AD, the FAA has approved the use of
clutch assembly, part number (P/N) 28-13401-4 (Formsprag CL 40526-10),
in addition to the earlier clutch assembly, P/N 28-13401-2 (Formsprag
CL 40526-8) as replacement clutch assemblies. Additionally, subsequent
to the issuance of AD 89-04-09, The Enstrom Helicopter Corporation
(Enstrom) issued Service Directive Bulletin (SDB) No. 0069, Revision A,
dated July 9, 1990, that contains an overhaul time interval for clutch
assemblies, P/N 28-13401-2 (Formsprag CL 40526-8) and P/N 28-13401-4
(Formsprag CL 40526-10). Also, AD 89-04-09 referenced neither Enstrom
Service Information Letter (SIL) No. 0084, dated December 19, 1978,
pertaining to checking the run-out of the main rotor pinion shaft nor
Enstrom SDB No. 0068, dated May 8, 1986, subsequently reissued July 9,
1990, pertaining to the retirement life of the clutch assembly.
Finally, a note contained in AD 89-04-09 incorrectly referenced SIL
``0038A''; the reference should have been SIL ``No. 0088, Revision A,
dated August 6, 1980.''
Since an unsafe condition has been identified that is likely to
exist or develop on other products of this same type design, the
proposed AD would supersede AD 89-04-09 to require initial and
repetitive inspections of certain clutch assemblies for bearing
roughness, noise, lock-up, or improper oil levels and, if necessary,
immediate replacement of the clutch assembly. Owner/operator checks are
proposed after engine start and rotor engagement to verify proper
operation of the clutch assembly and, after each engine shutdown, while
the main rotor is still turning down, to check for abnormal noise (such
as a clicking or racheting sound) from the upper pulley that houses the
clutch assembly. These proposed owner/operator checks do not require
the use of tools, precision measuring equipment, training, pilot
logbook endorsements, or the use of technical data not contained in the
AD. Additionally, these owner/operator checks are considered part of
the normal pilot ``Before Takeoff'' and ``After Landing'' checks and
were allowed by the existing AD. These owner/operator checks are
additional measures to ensure, between 25 hours TIS inspections, that
sufficient lubricants are maintained in the clutch assembly and not
lost through a leaking seal. These checks may be performed by an owner/
operator holding at least a private pilot certificate and must be
entered into the aircraft records showing compliance with this AD in
accordance with sections 43.11 and 91.417(a)(2)(v) of the Federal
Aviation Regulations. The proposed AD would also require replacement of
the clutch assembly at certain TIS intervals.
The FAA estimates that 162 helicopters of U.S. registry would be
affected by this proposed AD, that it would take approximately 2 work
hours per helicopter to accomplish the proposed actions, and that the
average labor rate is $55 per work hour. Required parts would cost
approximately $2,800 to overhaul or $10,500 for a zero-time clutch
assembly per helicopter. Based on these figures, the total cost impact
of the proposed AD on U.S. operators is estimated to be from $471,420,
if only overhauled clutch assemblies are installed, to $1,718,820, if
only zero-time clutch assemblies are used.
The regulations proposed herein would not have substantial direct
effects on the States, on the relationship between the national
government and the States, or on the distribution of power and
responsibilities among the various levels of government. Therefore, in
accordance with Executive Order 12612, it is determined that this
proposal would not have sufficient federalism implications to warrant
the preparation of a Federalism Assessment.
For the reasons discussed above, I certify that this proposed
regulation (1) is not a ``significant regulatory action'' under
Executive Order 12866; (2) is not a ``significant rule'' under the DOT
Regulatory Policies and Procedures (44 FR 11034, February 26, 1979);
and (3) if promulgated, will not have a significant economic impact,
positive or negative, on a substantial number of small entities under
the criteria of the Regulatory Flexibility Act. A copy of the draft
regulatory evaluation prepared for this action is contained in the
Rules Docket. A copy of it may be obtained by contacting the Rules
Docket at the location provided under the caption ADDRESSES.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Safety.
The Proposed Amendment
Accordingly, pursuant to the authority delegated to me by the
Administrator, the Federal Aviation Administration proposes to amend
part 39 of the Federal Aviation Regulations (14 CFR part 39) as
follows:
PART 39--AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C.
106(g); and 14 CFR 11.89.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by removing Amendment 39-6138 (54 FR
6391, February 10, 1989), and by adding a new airworthiness directive
(AD), to read as follows:
The Enstrom Helicopter Corporation (Enstrom): Docket No. 93-SW-27-
AD. Supersedes AD 89-04-09, Amendment 39-6138.
Applicability: Model F-28, F-28A, F-28C, F-28C-2, F-28F, 280,
280C, 280F, and 280FX series helicopters, certificated in any
category.
Compliance: Required as indicated, unless accomplished
previously.
To prevent failure of the main rotor transmission clutch
assembly (clutch assembly), loss of control of the main rotor
system, and subsequent loss of control of the helicopter, accomplish
the following:
(a) For Model F-28, F-28A, F-28C, F-28C-2, 280, and 280C series
helicopters, equipped with clutch assembly part number (P/N) 28-
13401-1 (Formsprag CL 40526-1 through-7) perform the following:
(1) Before the first flight of each day, before takeoff, gently
close the throttle, splitting the tachometer needles to verify
proper operation of the clutch assembly. If the tachometer needles
do not split, before further flight, inspect the clutch assembly in
accordance with paragraph (a)(4).
(2) At the conclusion of the last flight of each day, after
engine shutdown, while the main rotor is still running down, listen
for any abnormal noise (such as a clicking or racheting sound) from
the area of the upper pulley that houses the clutch assembly. If any
abnormal noise is heard from the clutch assembly, inspect the clutch
assembly in accordance with paragraph (a)(4).
(3) The operational checks required by paragraphs (a)(1) and
(a)(2) may be performed by an owner/operator holding at least a
private pilot certificate and must be entered into the aircraft
records showing compliance with this AD in accordance with 14 CFR
43.11 and 91.417(a)(2)(v).
(4) If any irregularities are noted while performing the
procedures required by paragraph (1) or (2), inspect the clutch
assembly to determine if it is locked-up, or if the upper pulley
will rotate. Rotate it in both directions while feeling for any
bearing roughness and listening for any bearing noise. The upper
pulley should free-wheel if rotated in a clockwise direction and
engage if rotated in a counterclockwise direction.
(5) Within the next 25 hours time-in-service (TIS) after the
effective date of this airworthiness directive (AD), make an entry
in the aircraft log book documenting the clutch assembly part
number, the number of hours TIS, and the date.
(6) Within the next 25 hours TIS after the effective date of
this AD, and thereafter at intervals not to exceed 100 hours TIS,
inspect the clutch assembly for proper oil level in accordance with
the appropriate maintenance manual. If there has been less than a
complete loss of oil, replenish the oil and service the clutch
assembly in accordance with The Enstrom Helicopter Corporation
Service Information Letter No. 0079A, dated February 14, 1980.
(7) If there has been a complete oil loss, or lock-up, noise, or
roughness are detected from the clutch assembly as a result of the
inspections required by this AD, before further flight, replace the
clutch assembly, P/N 28-13401-1 (Formsprag CL 40526-1 through-7),
with an airworthy clutch assembly, P/N 28-13401-2 (Formsprag CL
40526-8) or P/N 28-13401-4 (Formsprag CL 40526-10).
(8) For a clutch assembly, P/N 28-13401-1 (Formsprag CL 40526-1
through-7), that has 1,175 or more hours TIS on the effective date
of this AD, within the next 25 hours TIS, replace the clutch
assembly with an airworthy clutch assembly, P/N 28-13401-2
(Formsprag CL 40526-8) or P/N 28-13401-4 (Formsprag CL 40526-10).
(9) For a clutch assembly, P/N 28-13401-1 (Formsprag CL 40526-1
through-7), that has less than 1,175 hours TIS on the effective date
of this AD, replace the clutch assembly with an airworthy clutch
assembly, P/N 28-13401-2 (Formsprag CL 40526-8) or P/N 28-13401-4
(Formsprag CL 40526-10), prior to the clutch assembly accumulating
1,200 hours TIS.
Note: The clutch service information published in The Enstrom
Helicopter Corporation (Enstrom) Service Note No. 0027, dated
December 9, 1975; Enstrom Service Information Letter No. 0084, dated
December 19, 1978; Enstrom Service Information Letter No. 0079A,
dated February 14, 1980; Service Information Letter No. 0088,
Revision A, dated August 6, 1980, Enstrom Service Directive Bulletin
No. 0068, Revision A, dated July 9, 1990; and Enstrom Service
Directive Bulletin No. 0069, Revision A, dated July 9, 1990;
pertains to this AD.
(b) For Model F-28F, 280F, and 280FX series helicopters,
accomplish the following:
(1) Within the next 25 hours TIS after the effective date of
this AD, determine the part number of the clutch assembly.
(2) If a clutch assembly, P/N 28-13401-1 (Formsprag CL 40526-1
through-7), is found, before further flight, replace it with an
airworthy clutch assembly, P/N 28-13401-2 (Formsprag CL 40526-8) or
P/N 28-13401-4 (Formsprag CL 40526-10). The clutch assembly, P/N 28-
13401-1 (Formsprag CL 40526-1 through-7), is not approved for use on
Enstrom Model F-28F, 280F, or 280FX series helicopters.
(c) Installation of a clutch assembly, P/N 28-13401-2 (Formsprag
CL 40526-8) or P/N 28-13401-4 (Formsprag CL 40526-10), on Model F-
28, F-28A, F-28C, F-28C-2, F-28F, 280, 280C, 280F, and 280FX series
helicopters constitutes a terminating action for the requirements of
this AD.
(d) This AD establishes a retirement life of 1,200 hours TIS for
the clutch assembly, P/N 28-13401-1 (Formsprag CL 40526-1 through-
7). However, for clutch assemblies with 1,175 or more hours TIS on
the effective date of this AD, those clutch assemblies need not be
retired until on or before the accumulation of an additional 25
hours TIS.
(e) An alternative method of compliance or adjustment of the
compliance time that provides an acceptable level of safety may be
used when approved by the Manager, Chicago Aircraft Certification
Office, FAA. Operators shall submit their requests through an FAA
Principal Maintenance Inspector, who may concur or comment and then
send it to the Manager, Chicago Aircraft Certification Office.
Note: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Chicago Aircraft Certification Office.
(f) Special flight permits may be issued in accordance with
sections 21.197 and 21.199 of the Federal Aviation Regulations (14
CFR 21.197 and 21.199) to operate the helicopter to a location where
the requirements of this AD can be accomplished.
Issued in Fort Worth, Texas, on September 6, 1994.
Eric Bries,
Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 94-22627 Filed 9-12-94; 8:45 am]
BILLING CODE 4910-13-P
